1974–75 South-West Indian Ocean cyclone season

Intense tropical cyclone (MFR)
	<img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/35/Temporary_cyclone_south.svg/150px-Temporary_cyclone_south.svg.png" decoding="async" width="150" height="125" class="mw-file-element" data-file-width="180" data-file-height="150"> <img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Blandine_1975_track.png/150px-Blandine_1975_track.png" decoding="async" width="150" height="107" class="mw-file-element" data-file-width="2700" data-file-height="1920">
Duration	January 6 – January 12
Peak intensity	175 km/h (110 mph) (10-min);; 980 hPa (mbar)

Tropical disturbance (MFR)
	<img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/35/Temporary_cyclone_south.svg/150px-Temporary_cyclone_south.svg.png" decoding="async" width="150" height="125" class="mw-file-element" data-file-width="180" data-file-height="150"> <img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/36/Adele_1974_track.png/150px-Adele_1974_track.png" decoding="async" width="150" height="93" class="mw-file-element" data-file-width="2700" data-file-height="1669">
Duration	December 23 – December 24
Peak intensity	Winds not specified;;

1974–75 South-West Indian Ocean cyclone season
1974–75 South-West Indian Ocean cyclone season
	Season summary map
Seasonal boundaries
First system formed	23 December 1974
Last system dissipated	22 April 1975
Strongest storm
Name	Gervaise
• Maximum winds	120 km/h (75 mph); (10-minute sustained)
• Lowest pressure	951 hPa (mbar)
Seasonal statistics
Total disturbances	10
Total depressions	8
Total storms	6
Tropical cyclones	5
Intense tropical cyclones	2
Total fatalities	9 total
Total damage	Unknown
Related articles
	1974–75 Australian region cyclone season; 1974–75 South Pacific cyclone season;
	South-West Indian Ocean tropical cyclone seasons; 1972–73, 1973–74, 1974–75, 1975–76, 1976–77

The 1974–75 South-West Indian Ocean cyclone season was an average cyclone season. The season officially ran from November 1, 1974, to April 30, 1975.

Systems

Tropical Disturbance Adele

Adele existed from December 23 to December 24.

Intense Tropical Cyclone Blandine

Blandine existed from January 6 to January 12.

Tropical Cyclone Camille

Tropical cyclone (MFR)

Duration	January 10 – January 21
Peak intensity	150 km/h (90 mph) (10-min); 995 hPa (mbar)

This system formed southeast of the Seychelles on January 7 before becoming disorganized while interacting with northern Madagascar. The system redeveloped as a hurricane-force cyclone in the northern Mozambique Channel on January 16 before moving southeast into Madagascar on January 19.^[1]

Intense Tropical Cyclone Robyn–Deborah

Intense tropical cyclone (MFR)

Duration	January 14 – January 24
Peak intensity	185 km/h (115 mph) (10-min); 960 hPa (mbar)

This system existed from January 14 to January 24.

Tropical Depression Elsa

Tropical depression (MFR)

Duration	January 25 – January 27
Peak intensity	55 km/h (35 mph) (10-min);

Elsa existed from January 25 to January 27.

Tropical Disturbance Fernande

Tropical disturbance (MFR)
Tropical depression (SSHWS)

Duration	February 1 – February 1
Peak intensity	55 km/h (35 mph) (1-min);

This storm lasted for only 18 hours on February 1.

Intense Tropical Cyclone Gervaise

Intense tropical cyclone (MFR)
Category 4 tropical cyclone (SSHWS)

Duration	February 1 – February 10
Peak intensity	195 km/h (120 mph) (10-min); 951 hPa (mbar)

The origins of Cyclone Gervaise were in early February 1975 from a circular area of convection, or thunderstorms, located in the Intertropical Convergence Zone southwest of Diego Garcia in the south-west Indian Ocean. The system organized as it moved generally to the southwest, a trajectory it would maintain for several days due to a subtropical ridge to its southeast, and an area of low pressure near the Mascarene Islands. On February 2, the Mauritius Meteorological Services^[a] named the storm Gervaise. Two days later, the storm attained hurricane status, or maximum sustained winds of at least 120 km/h (75 mph).^[3] Late on February 5, Gervaise passed about 100 km (60 mi) southeast of St. Brandon. Continuing southwestward, the cyclone struck Mauritius on February 6, with the calm of the eye lasting for three hours. That day, the American-based Joint Typhoon Warning Center (JTWC)^[b] estimated peak winds of 130 km/h (80 mph).^[4] On February 7, Gervaise passed about 130 km (80 mi) southeast of Réunion. The track shifted to the south and southeast over time, steered by a passing cold front. On February 10, Gervaise dissipated within the cold front.^[3]

Gervaise first affected St. Brandon, producing wind gusts of over 100 km/h (62 mph), along with heavy rainfall. Cyclone Gervaise killed 10 people during its passage of Mauritius. Its strongest wind gusts occurred after the passage of the eye, peaking at 280 km/h (170 mph) at Mon Desert. Heavy rainfall affected the island for several days, reaching 674 mm (26.5 in) at Grosse Roche. The high winds knocked down power lines, radio transmission with Vacoas for 24 hours, and many crops. About 25% of the island's sugar cane crop was lost. The storm damaged several houses, leaving thousands homeless. The cyclone last affected Réunion, where it produced wind gusts of 180 km/h (110 mph). Gervaise also dropped heavy rainfall on the island, reaching 548 mm (21.6 in) at Plaine des Cafres.^[3] It caused substantial damage to properties, vegetation and wildlife. Moored yachts around the coast were washed hundreds of yards inland in places due to the storm surge and in the Mauritian capital Port Louis, a cargo ship of ca. 10,000 tonnes was washed up on to the quay. 34 injured, 3,706 homeless.

Tropical Cyclone Helose

Tropical cyclone (MFR)

Duration	February 19 – February 26
Peak intensity	150 km/h (90 mph) (10-min); 985 hPa (mbar)

Helose existed from February 19 to February 26.

Severe Tropical Storm Ines

Severe tropical storm (MFR)
Tropical storm (SSHWS)

Duration	March 9 – March 19
Peak intensity	110 km/h (70 mph) (10-min); 985 hPa (mbar)

Ines existed from March 9 to March 19.

Severe Tropical Storm Junon

Severe tropical storm (MFR)
Tropical storm (SSHWS)

Duration	April 18 – April 22
Peak intensity	95 km/h (60 mph) (10-min); 1005 hPa (mbar)

Junon existed from April 18 to April 22.

Season effects

Name	Dates	Peak intensity			Areas affected	Damage (USD)	Deaths	Refs
Name	Dates	Category	Wind speed	Pressure	Areas affected	Damage (USD)	Deaths	Refs
Norah	November 1 – 4, 1974	Severe tropical storm	95 km/h (60 mph)	988 hPa (29.18 inHg)	Christmas Island, Cocos Island	None	None	^[5]
Adele	December 23 – 24, 1974	Tropical disturbance	Not specified	Not specified	Christmas Island, Cocos Island	None	None	^[6]
Blandine	January 6 – 12, 1975	Intense tropical cyclone	175 km/h (110 mph)	980 hPa (28.94 inHg)	None	None	None	^[6]
Camille	January 10 – 21, 1975	Tropical cyclone	150 km/h (90 mph)	995 hPa (29.38 inHg)	None	None	None	^[6]
Robyn–Deborah	January 14 – 24, 1975	Intense tropical cyclone	185 km/h (115 mph)	965 hPa (28.50 inHg)	None	None	None	^[6]
Elsa	January 25 – 27, 1975	Tropical depression	55 km/h (35 mph)	Not specified	None	None	None	^[6]
Fernande	February 1 – 1, 1975	Tropical disturbance	55 km/h (35 mph)	Not specified	None	None	None	^[6]
Gervaise	February 1 – 10, 1975	Intense tropical cyclone	195 km/h (120 mph)	951 hPa (28.08 inHg)	None	None	None	^[6]
Helose	February 19 – 26, 1975	Tropical cyclone	150 km/h (90 mph)	985 hPa (29.09 inHg)	None	None	None	^[6]
Ines	March 9 – 19, 1975	Severe tropical storm	110 km/h (70 mph)	985 hPa (29.09 inHg)	None	None	None	^[6]
Junon	April 18 – 22, 1975	Severe tropical storm	95 km/h (60 mph)	1005 hPa (29.68 inHg)	None	None	None	^[6]
Season aggregates
11 systems			195 km/h (120 mph)	951 hPa (28.08 inHg)

Notes

^ Météo-France's meteorological office in Réunion (MFR) is the official Regional Specialized Meteorological Center for the South-West Indian Ocean, tracking all tropical cyclones from the east coast of Africa to 90° E. The Mauritius Meteorological Office is responsible for naming storms in the eastern east of 55° E.^[2]
^ The Joint Typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force task force that issues advisories for storms in the basin.

References

^ Dick DeAngelis. "Hurricane Alley". Mariners Weather Log. 19 (3): 154.
^ Philippe Caroff; et al. (April 2011). Operational procedures of TC satellite analysis at RSMC La Réunion (PDF) (Report). World Meteorological Organization. pp. 4–5. Retrieved 2013-10-27.
^ ^a ^b ^c Hurricane Gervaise, 1–9 February. National Climatic Data Center (Report). Global tropical/extratropical cyclone climatic atlas. 1996. Retrieved February 3, 2019.
^ Kenneth R. Knapp; Michael C. Kruk; David H. Levinson; Howard J. Diamond; Charles J. Neumann (2010). 1975 Tropical Cyclone Gervaise (1975033S11073). The International Best Track Archive for Climate Stewardship (IBTrACS): Unifying tropical cyclone best track data (Report). Bulletin of the American Meteorological Society. Retrieved February 3, 2019.
^ "1974 Tropical Cyclone Norah (1974301S08105)". International Best Track Archive for Climate Stewardship. Retrieved May 8, 2022.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j "Saison 1974-1975 des perturbations tropicales dans l'océan indien du sud-ouest" [1974-1975 Tropical disturbance season in the southwestern Indian Ocean]. Météorologie Maritime (in French). No. 87. 1976. pp. 40–48. ISSN 0222-5123.

[3] Météo-France's meteorological office in Réunion (MFR) is the official Regional Specialized Meteorological Center for the South-West Indian Ocean, tracking all tropical cyclones from the east coast of Africa to 90° E. The Mauritius Meteorological Office is responsible for naming storms in the eastern east of 55° E.^[2]

[5] The Joint Typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force task force that issues advisories for storms in the basin.

[1] Dick DeAngelis. "Hurricane Alley". Mariners Weather Log. 19 (3): 154.

[car-2] Philippe Caroff; et al. (April 2011). Operational procedures of TC satellite analysis at RSMC La Réunion (PDF) (Report). World Meteorological Organization. pp. 4–5. Retrieved 2013-10-27.

[g-4] Hurricane Gervaise, 1–9 February. National Climatic Data Center (Report). Global tropical/extratropical cyclone climatic atlas. 1996. Retrieved February 3, 2019.

[bt-6] Kenneth R. Knapp; Michael C. Kruk; David H. Levinson; Howard J. Diamond; Charles J. Neumann (2010). 1975 Tropical Cyclone Gervaise (1975033S11073). The International Best Track Archive for Climate Stewardship (IBTrACS): Unifying tropical cyclone best track data (Report). Bulletin of the American Meteorological Society. Retrieved February 3, 2019.

[7] "1974 Tropical Cyclone Norah (1974301S08105)". International Best Track Archive for Climate Stewardship. Retrieved May 8, 2022.

[1974-75-8] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j "Saison 1974-1975 des perturbations tropicales dans l'océan indien du sud-ouest" [1974-1975 Tropical disturbance season in the southwestern Indian Ocean]. Météorologie Maritime (in French). No. 87. 1976. pp. 40–48. ISSN 0222-5123.

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